Control mechanism for shuttle changing looms



Dec. 28, 1937. w. w. ROBERTSON 2,103,823

' CONTROL MECHANISM FOR SHUTTLE CHANGING LOOMS I Filed Aug. 5, 1955 4 Sheets-Sheet 1' William w. Robertson Attorneys Dec. 28, 1937. ROBERTSON '2,103,s23

CONTROL MECHANISM FOR SHUTTLE CHANGING LOOMS Filed Aug. 5, 1935 '4 Sheets-Sheet 2 Inventor William W. Rober'ison 1380- 2 1937-v w. w. ROBERTSON CONTROL MECHANISM FOR SHUTTLE CHANGING LOOMS Filed Aug. 5, was 4 Sheets-Sheet 3 inventor Wylham W. Robertson Attor neyS c- 1937- w. w. ROBERTSON CONTROL MECHANISM FOR SHUTTLE CHANGING LOOMS Filed Aug. 5, 1955 4 Sheets-Sheet 4 lnve ntor v William W. Roberfson 0% AK ovrneys Patented Dec. 28, 1937 CONTROL MECHANISM FOR SHUTTLE CHANGING LOOMS William W. Robertson, Marlboro, Mass., assignor to Crompton & Knowles Loom Works,

' Worcester,- Mass., a corporation of Massachu- Application August 5, 1935, Serial No. 34,660

Claims,

This application is a continuation in part of my copending application Serial No. 14.805 filed April 5, 1935 for 21; Shuttle changing loom.

This invention relates to improvements in shuttle changing looms and it is the general object of the invention to prevent the completion of a shuttle changing operation if the active depleted shuttle should fail to reach its shuttle box at the shuttle changing side of the loom.

In the type of loom to whichmy invention moreparticularly relates weft detecting mechanism is located on that side of the loom opposite the shuttle changing mechanism and acts upon substantial depletion of weft to initiate change in the shuttles. This change involves the stopping of the loom, the-ejection of the depleted shuttle, the placing of. a fresh reserve shuttle into active position, and restarting the loom. These several operations are accomplished by means of a so-called changeshaft having cams which operate in proper sequence to perform the necessary operations. The loom is so controlled that it comes to rest during the replenishi'ng period with the lay in back position. If the active shuttle should fail to be boxed on the magazine side the shuttle changing mechanismmight, unless otherwise controlled, place a reserve shuttle into action so that the protector mechanism would be moved to running position to permit resumption of weavingQand a shuttle smash would result due to the fact that the depleted shuttle would still be in the shed. It is an important object of my present invention to prevent the shuttle changing mechanism from placing a reserve shuttle into the shuttle box when the active depleted shuttle fails to be correctly boxed.

In carrying a convenient embodiment of my invention into effect I provide a control hook to prevent complete rearward. movement of the conveyor if the active shuttle fails .to reach its shuttle box. The outgoing shuttle must be removed from the shuttle box before the conveyor can replace it with a fresh shuttle. In order that the interval between ejection and replacement may not interfere with the changing operation, I rely upon the protector finger to unlock.v the shuttle changer when the active shuttle reaches its box before ejection. This happens in sufficient time to permit a complete indication to be givenbefore the shuttle changer canget beyond control of the lock.

It is a further object of my present invention to provide mechanism which-sets the hook in stopping position before arrival ofv the. shuttle (o1. ism-231 at the magazine end, the protector thereafter returning the hook to non-holding position by control fingers set by the same deviceswhicli stop the loom for shuttle change. I When the active shuttle is picked from the detector side of the 100m neither of its shuttle boxes will be occupied and the protector finger will therefore move temporarily to stopping position and I arrange the timing of the parts so that'a control finger will be moved to controlling or stopping position prior to arrival of the shuttleat the magazine end. If the shuttle fails to be boxed the control finger remains in position to keep the hook in conveyor restraining position, but if the shuttle is correctly boxed it acts before its ejection can begin to move the controlling finger and therefore the hook out of arresting position. Y The last operation of the shuttle changing period is to restart the loom and if shuttle change has been prevented as hereinbefore'de scribed I provide mechanism to prevent restart-- ing, this mechanism preferably being actuated through the same hook which restrains the conveyor and bya force derived from the latter.

While I have shown the invention I have as Y sociated with a double shuttle loom employing two shuttles to be picked simultaneously for the weaving of a double fabric, yet I donot wish to be limited to such a loom, inasmuch as certainfeatures of my invention operate independently of the number of shuttles which arrive at a given time on the shuttle changing side of the loom and themechanism shown for either the upper or the lower shuttle box can be used for a single shuttle loom.

With these and other objects in view which will appear as the description proceeds, my invention resides in the combination and arrangement of parts hereinafter described and set forth in the claims.

ent positions,

Fig. 4 is a vertical section on an enlarged scale taken on line 4-4, Fig. 1,

Fig. 5 is a detailed horizontal section on line 5-5, Fig. 4,

Fig. 6 is a detailed horizontal position on line 65 of Fig. 2,

Fig. '7 is a schematic view showing the operating relations of certain parts shown in Fig. 1,

Fig. 8 is a plan View partly in section taken in the direction of arrow 8, Fig. 7, i

Fig. 9 is a vertical section on line 99 of Fig. 7,

Fig. 10 is a detail front elevation looking in the direction of arrow Iii, Fig. l, on an enlarged scale,

Fig. 11 is a side elevation looking in the direction of arrow ll, Fig. 10,

1 boxes l2 and 13, respectively, having binders I 4 which cooperate with protector fingers I5. Upper and lower shuttles S and S are preferably picked together into and out of the shuttle boxes and the protector fingers move with daggers IS in the usual manner with protector rods I! so that as the lay moves around its axis I8 these daggers will operate to stop the loom if one or the other of the shuttle boxes is unoccupied as the lay approaches its forward position, which is to the left of that shown in Fig. 1.

Front and back reserve shuttle magazines 2! and 22, respectively are held in fixed position on a bracket 2!! fixed to the loom frame. Transfer heads or conveyors and 26 for the front and back magazines, respectively, are each provided with a shuttle supporting shelf 2! to receive a reserve shuttle from the corresponding magazine. Front and back conveyor levers 3B and 3|, respectively, pivot about a stud 32 and are normally urged'to move rearwardly or to the right, Fig. 1, toward the lay by heavy tension springs 33 anchored at their lower ends to fixed structure. The front conveyor is connected to an operating rod 35 the forward end of which is attached to a conveyor operating lever 36 pivoted as at 34 and having operative relation with a cam 31 secured to and rotatable with a change shaft 38. The latter is normally at rest but rotates during the shuttle changing period. The rear conveyor lever 3! is connected by an operating rod 39 to a second conveyor operating lever 4!] likewise pivoted at 34 and coacting with a cam 4| also secured to the change shaft 38.

When the shuttle changing mechanism is at rest the cams are approximately in the position shown in Fig. 1, but as the shaft 38 rotates in the direction of arrow A, Fig. 1, the conveyor levers are first given a slightforward motion to the left as viewed in Fig. l'by cam risers a and are maintained in this position by dwells 45, after which continued rotation of the shaft presents declining cam-areas 4-6 to the levers 36 and 49 to permit the springs 33 to move the conveyors rearwardly toward the lay to place reserve shuttles in the shuttle boxes. Continued rotation of shaft 33 acts to return the conveyors to their forward positions by rises I). These motions occur during a normal shuttle change and the springs 33 supply the forces which actually move the conveyors rearwardly.

Prior to movement of the conveyors toward the lay a box front 41 on the lay is elevated to permit ejection of the depleted active shuttles from the boxes I2 and Hi. When the box front rises and the depleted shuttles move forwardly the protector fingers will move in or to their stopping position, this action taking place before the conveyors have had any considerable rearward motion. The

. operating connections for moving the box front 47 are not set forth herein but may if desired be as set forth in patent to Cowan No. 1,906,544.

Figs. 7, 8 and 9 show the mechanism for controlling the stopping of the loom. A solenoid 50 is normally deenergized so that a dog 5| lies below the path of a knock-off lever 52 regularly reciprocated by a cam 53 ona shaft 54 of the loom driven as indicated in Fig. '7. So long as both shuttles have sufficient weft the solenoid is deenergized, but when the detector mechanism not shown calls for a change because of weft exhaustion in either shuttle the solenoid is energized by connections not shown to raise the dog into the path of lever 52, whereupon rod 55 is given a longitudinal movement to the left as viewed in Fig. 9 to rock two arms 42 and 43 secured to a short shaft 44 in bearing 48, see Figs. 1 and 9. Rod 63 is pivoted to arm 43, and when moved forwardly, to the left in Fig. 7, rocks a bell crank lever in a clock- Wise direction about a fixed axis 6i against the action of spring 64.

An arm 65 of lever 60 has a lip 66 lying under an arm Bl pivoting about fixed axis 5! and connected to a rod 68 extending upwardly and attached to a rock shaft 69 mounted in bearings 76. A finger li secured to shaft 69 carries a depending rod 72 connected to a similar finger 13 on a shipper shaft 14. The latter rocks in bearings one of which is shown at 75, and extends rearwardly to shipper mechanism not shown but operative to stop the loom when the shaft 14 4 is rocked by down motion of rod 72. Forward motion of rod 63 acts through lip 55, arm 67 and rod 68 to give the necessary down motion to rod 12. Cam 53 is set on shaft 53 so as to cause the stopping impulse to lever 66 just after the shuttles are picked from the side of the loom opposite the magazines, the loom coming to rest with the lay in rear position, as is common in shuttel changing looms of this type.

Pivoted to arm 65 is a depending rod 55 pivoted at its lower end to one end of a lever 23 to the other end of which is attached an upright rod 24. Lever 23 is pivoted between its ends so that up motion'of rod 55 causes down mo tion of rod 24, and the latter is connected to an arm 51 which moves a finger 58 to connect a regularly moving disk 56 to a clutch disk 28 fast on change shaft 38. The particular form of clutch for shaft 38 forms no part of my invention and it is sufficient for present purposes to state that the normally stationary change shaft is started on a complete slow rotation whenever rod 63 actsto lift rod 56. Thus it is that excitation of solenoid 50 causes loom stoppage, rotation of shaft 38, and end thrust of rod 53, the latter being particularly useful in carrying out my invention.

It should be borne in mind that lever 52 must be given its full swing with cam 53 in the dotted posi tion of Fig. 9 before the shipper is thrownv to stopping position, and that a slight inevitable runoverof the loom. will carry the cam to the dot and dash position of that figure, thereby permitting spring 64 to return rod 63 to its normal position to the right, as in Fig. '7, as the 100m stops. Arm 65 candrop-without-return-rotation with the setting arms 96' and 91 down and the of shaft 14; and onceshaft38 'starts-to rotate it'is independent of rods 56 and -63, and will continue its'rotation throughout the shuttle changing period; I

Part ofthe mechanism thus, far described of itself forms no part of my present invention and it is sufficient to state that indicationofweftexhaustion by the detector mechanism on that side of the loom opposite the conveyors will result in operation of solenoid 5i] and rod 63. For further reference as to the structure and operation of the solenoid referencemay be had to, Payne Patent No. 1,873,465, while the change shaft clutch may be seen in greater detail in the aforesaid Cowan patent. ,7

The controller to prevent. a shuttle change" is shown in Figs. '1, 7, 13' andle. A fixed stand 80 on the support 20 has pivoted thereto as at iii an arm 82 the upper 'end of which is connected to a forwardly extending restarting controller rod 83. At an intermediate part of arm 82 there is pivoted as at 19 a hook 84 which moves with an upstanding short finger 85. This finger is pivotally connected to the forward end of a rod 86 which has two threaded forks 8i and 88, respectively, see Fig. 6.

A stand.'90,see Figsl, 2 and 3, is secured to the loom frame and carries a pivot stud 9| .on which are pivotally mounted two hook. controlling, arms 92 and 93, respectively, slottedto fit around forks 8'! and 88, respectively. Arm 92'carries a resetting finger 94 which projects forwardly, while a similarfinger 95 is movable with arm 93. A setting cam arm 96 isrigid with arm 92, while a second setting cam armAl-l moves with arm 93. These cam arms projectrearwardly and are arranged for cooperation with-acarn block 93 fixed to but adjustable longitudinally along rod 63.

The resetting fingers Stand 95 .are bent upwardly as at 99 to cooperate with lugs Hi0 carried by lifter arms NH and H32 movable, respectively, with the protector fingers for the upper and lower shuttle boxes, see Figs. 4 and 5. The arms lfll and I02 move back and'forth with the lay and relatively'to the fingersfi iand. 95. Each of the arms 92*and 93 has attached thereto a flexible friction arm movable between friction springs I96 carried by stand. 90 to hold said arms yieldingly in any position to which they may be moved by block 98 or lugs. I09. A light spring l0! connected to the'top of finger 85 counterbalances the weight of the hook'and acts to move the rod 86 forwardly, or to the left in Fig. l, but is not strong enough to disturb the friction devices just described. An adjustable screw 15 on arm 82 is engaged by finger 85 when the lattermoves to the left, Fig. 13, so that spring I011 acts not only to lift hook 84 but alsoholds it yieldingly in forward position. v

As long as the shuttles. are boxed at the detector end thelifter arms ldl'and Hi2 will be raised and would therefore interfere with the down motion of the resettingfin'gers 95' and 95 induced by the cam block 98. To prevent this interference the lugs I09 do not reach the resetting fingers as the lay moves rearwardly until after picking, hence the lugs have time to move down before they can engage the resetting fingers and the latter can retain a low setting. Loom stoppage for shuttle change can therefore be initiated early in the backward stroke of the lay.

In operation, the normal position of the parts would be with the hook 84-raisecl and the arms 92 and 93 in left hand position as shown in Fig. 1

block or'mem-ber 98 in rear position or-to the righta-s viewed in Fig. 1. When rod 63 moves forwardly-at the-beginning of the shuttle changing period the block- 98 will be carried from the full to-thedotted line position shown in Fig. '7 and cause inclinedsurface I08 of the block to raise the setting arms and rock arms 92 and 93 to the left, Fig. 2, to cause lowering of the resetting arms 94 and 95.; Arms 92 and 93 also move rod 8 6; rearwardly and lower the hook 84 into-alignment with lugs 78 on the conveyors. As already described the block 98 will then move back from the full to the dotted line position shown in Fig. 2 because of movement of cam 53 beyondthe kIlOCk-OfiLIGVGI 52, but the friction springs 15 will hold'th'e resetting fingers elevated. Hook 8.4, which was moved down when arms 92 and 93 moved to the right, Fig. 2, remains in this position aligned withlugs 18 on the conveyor levers.

A shorttime thereafter, assuming that both shuttles arrive at the magazine side correctly, the

lugs Hill will be raised to lift theresetting fingers {Hand 95,.moving the arms 92, and93 forwardly, to the left in Fig. 1, and permitting spring lll'l to rock arm 85 in a left hand direction to lift the hook 84 above the lugs 18.

. attemptto move rearwardly their lugs 18 will engage the hook and shuttle change will be prevented. The conveyor levers will continue to move rearwardly a short distance, moving the book 84 back and carrying the rod 83 also rearwardly. v

In order to restart the loom after shuttle change and prevent restarting if; the shuttle change has been prevented, I provide the-,mechanism shown particularly in Figs. 1, 10; 11 and 12. The change shaft has secured thereto a restarting cam H 0 to rock a restarting lever I II on fixed pivot H2 and having an upstanding arm H3 to which isattached a tension spring H4. The latter isconnected to the bottom of a vertical slide bar H5 having a slot H6 to receive a pin H1 on'lever Ill. The slot and spring provide a giveway connectionbetween cam H!) and the bar.

The upper end of the bar has a shoulder H8, see Fig. 12, lying under a web H9 of a yoke I29 through which the upper end l2! of the bar passes. The yoke guides the barv and is of sufficient width to permit the bar to move far enough to the right from the position shown in full lines, Fig. 12, to permit the shoulder to move out of vertical alignment with the web H9. The yoke has a hub I22 fastened to restarting shaft [4. Near the end of the shuttle changing period the cam Hil will rock lever III in aclockwise direction, Fig. 1, andif the transfer has been normal with rod 83 forward, spring M will raise the bar to effect rocking of shaft M by the shoulder and web, thus causing the loom to resume running.

Should shuttle change be interrupted as already described, I provide means to prevent restarting.

The rod 83 has its forward end slotted at l3l to receive the reduced top end [2| of the restarting bar, see Fig. 11. Spring H4 normally holds the shoulder under the web, but when the conveyors start the first part of their rearward motion they move the hook rearwardly a slight amount, as already described, to cause backward motion of arm 82, thereby moving the rod 83 and the top of the bar H5 rearwardly to place shoulder H8 out of vertical alignment with web H9, as shown in dotted lines in Fig. 12.

In the latter part of the shuttle changing period the conveyor levers will move forwardly to move the lugs i3 away from the hook but the gradual rise on cam H will have lifted shoulder i is slightly above web H9 before the hook starts to return forwardly to its normal front position. Movement of lugs 18 will therefore not cause loss of the setting of rod 83 and bar I I5.

Operation of lever l l l by cam I M at the end of the shuttle changing period will therefore result in an idle upward motion of bar H and the shipper shaft M will remain at rest to prevent loom restarting. During the first part of the shuttle changing period, when upper end |2l of the bar moves to the right under action of the hook, said end engages the right part of the yoke !20 as in dotted lines, Fig. 12, and further rearward motion of rod 83 is prevented, hook 84 being thus held to prevent further rear motion of the conveyors.

From the foregoing it will be seen that I have provided means which move at the beginning of the shuttle changing period to a position to prevent shuttle change and in addition have provided mechanism to be operated by the arrival of both shuttles to move the restraining element back to normal non-restraining position. If either shuttle fails to be boxed, however, the restraining element will remain in position to prevent the conveyor levers from moving toward the lay. These controls are exercised through the protector fingers as soon as the shuttles are boxed and therefore before the ejection of the active shuttle can interfere with the control mechanism. Furthermore, since the restraining hook is moved out of holding position upon the arrival of both shuttles at the magazine side of the loom it is immaterial what time relation exists between the ejection of the depleted shuttles and the movement of the conveyors and the latter can start their backward movement while the lugs 73 are still in front of the hook 84 after the depleted shuttles have been ejected from the shuttle boxes and the protector fingers have moved to stopping position. It will be seen that this latter movement of the protector fingers does not in any way affect the setting of the hook. Furthermore, when shuttle change is prevented means are provided to prevent the loom from restarting, preferably by the hook which restrains the conveyor lever.

The term shuttle changing period used in the foregoing description refers to that period in loom operation in which the depleted shuttle is discharged and the reserve shuttle is placed on the lay. This period may begin as soon as the lay comes to rest in the rear position and last until the restarting mechanism resumes loom operation, although I do not wish to be limited to a loom which necessarily stops for shuttle replacement.

While I have shown herein mechanism to prevent restarting of the loom should the active shuttles fail to be boxed at the beginning of the shuttle changing period, yet the same is not claimed herein since such features are described and claimed in my co-pending application Serial No. 34,661 filed Aug. 5, 1935.

Having thus described my invention it will be seen that changes and modifications may be made therein by those skilled in the art without departing from the spirit and scope of the invention and I do not wish to be limited to the details herein disclosed, but What I claim is:

1. In a shuttle changing loom having a shuttle box from which a depleted shuttle is removed during the shuttle changing period, protector mechanism to be positioned by a shuttle in the shuttle box, stopping means to stop the loom during the shuttle changing period, shuttle changing mechanism effective to place a reserve shuttle into the shuttle box, preventing mechanism to arrest operation of the shuttle changing mechanism, control means for the preventing mechanism, actuated by the stopping means to move the preventing mechanisminto arresting relation with respect to the shuttle changing mechanism, the protector mechanism thereafter operative when the shuttle box is occupied by a depleted shuttle to actuate the control means and thereby cause the latter to move the preventing mechanism out of arresting relation with respect to the shuttle changing mechanism.

2. In a shuttle changing loom which is at rest during the shuttle changing period, a shuttle box on the lay, shuttle changing mechanism to place a reserve shuttle into the shuttle box during the shuttle changing period, preventer means capable of arresting operation of the shuttle changing mechanism, loom stopping means, protector means, and control connections between the preventing means and the stopping and protector means effective by a control exerted by the stopping means to move the preventer means into arresting relation relatively to the shuttle changing mechanism and thereafter effective by a control exerted by the protector means to move the preventer means out of arresting relation relatively to the shuttle changing mechanism if a shuttle is in the shuttle box at the beginning of the shuttle changing period.

3. In a shuttle changing loom operating with a shuttle box from which a depleted shuttle is removed during the shuttle changing period, a reserve shuttle conveyor, a preventer for the shuttle conveyor normally out of arresting relation with respect to the shuttle conveyor, means operative prior to removal of the depleted shuttle from the shuttle box to move the preventer into position to arrest operation of the shuttle conveyor, and means operated by arrival of the depleted shuttle in the shuttle box to move the preventer out of arresting relation with respect to the shuttle conveyor.

4. In a shuttle changing loom having a lay and a shuttle box, protector mechanism, stopping means to cause the loom to be at rest during a shuttle changing period, shuttle changing mechanism, a conveyor forming part of the shuttle changing mechanism, preventing mechanism to arrest operation of the conveyor, and a controller for the preventing mechanism movable by the stopping mechanism when the latter arrests loom operation to set the preventer mechanism to prevent operation of the conveyor, said controller also operatively related to the protector mechanism to be moved by the latter to render the preventing mechanism capable of moving out of restraining relation with respect to the conveyor when the shuttle box is occupied by a shuttle.

5. In a shuttle changing loom having a lay and shuttle box from which a depleted shuttle is removed at the beginning of a shuttle changing period, stopping mechanism to cause the loom to be at rest during the shuttle changing period, a reserve shuttle conveyor, preventing means to arrest operation of the conveyor and normally out of arresting position with respect to the conveyor,'a controller to connect the stopping mechanism and the preventing mechanism to move the latter into restraining relation with respect to the conveyor, and protector mechanism effective by presence of a depleted shuttle in the shuttle box to move the controller in a direction to render the preventing mechanism capable of moving out of restraining relation with respect to the conveyor.

6. In a shuttle changing loom having a shuttle box from which a depleted shuttle is removed during the first part of a shuttle changing period, shuttle changing mechanism, a conveyor forming part of the shuttle changing mechanism to move a reserve shuttle from the shuttle changing mechanism to the shuttle box, preventing mechanism capable of arresting operation of the conveyor, stopping means to cause the loom to be at rest during the shuttle'changing period, protector mechanism to detect the presence of a depleted shuttle in the shuttle box, and operative connections between the preventing mechanism and thestopping means and protector mechanism efiective first to move the preventing mechanism into position to arrest operation of the conveyor 7 by a force derived from the stopping means and thereafter effective by a control exercised by the protector mechanism to effect movement of the preventing means out of restraining position with respect to the conveyor when the protector mechanism detects presence of a depleted shuttle in the shuttle box.

'7. In a shuttle changing loom which efiects a shuttle changing operation in a given period, a shuttle advancer normally operating at an intermediate point between the beginning and ending of the period, preventing means to interrupt motion of the advancer, means operative prior to said intermediate point to move the preventing means into arresting relation with respect to the shuttle advancing means to prevent completion of the normal movement of said reserve shuttle moving means, and mechanism operated by the depleted active shuttle when arriving at the end of the loom adjacent the reserve shuttle advancing means and subsequent to operation of the preventing means but prior to said intermediate point to move the preventing means out of preventing relation with respect to the reserve shuttle advancing means.

8. In a shuttle changing loom which is at rest during the shuttle changing period, a shuttle changer, preventing means therefor, a setting element, means operative when the loom comes to rest at the beginning of the shuttle changing period to move into relation with respect to the setting element to move the latter from normal to abnormal position and then move out of operative relation with respect to the setting element, protector mechanism to move the setting element back to normal position when the active depleted shuttle arrives at the shuttle changer side of the loom, operative connections between the setting element and preventer means effective to move the preventing means into arresting relation with respect to the shuttle changer when the setting element is in abnormal position, and means to move the preventing means out of arresting relation with respect to the shuttle changer when the setting element is returned to normal position by the protector mechanism.

9. In a shuttle changing loom which is at rest during the shuttle changing period, a shuttle changer, preventing means normally out of holding relation with respect to the changer, stopping means for the loom, a setting element normally in running position, connections between the setting element and the preventing means, a member movable by the stopping means to give the setting element a movement to position the preventing means in restraining relation with respect to the shuttle changer, and means operative thereafter by the depleted shuttle when ar-v riving at the shuttle changer side ofthe loom to return the setting element to running position, whereupon the preventing means moves out of restraining relation with respect to the shuttle changer.

10. In a shuttle changing loom having a shuttle box from which a depleted shuttle is removed during the shuttle changing period, a protector finger movable to running position when the depleted shuttle is in the shuttle box and movable to stopping position when the depleted shuttle has been removed from the shuttle box, a shuttle changer, a preventer to arrest operation of the shuttle changer, a controller for the preventer movable to shuttle changing position by the protector finger when the latter moves to running position, means to move the preventer out of arresting position as long as the controller is in shuttle changing position, and means additional to the protector finger to hold the controller in shuttle changing position after the, protector finger moves to stopping position due to removal of the depleted shuttle from the shuttle box.

WILLIAM W. ROBERTSON; 

